Patch (or microstrip) antennas typically include a flat metal sheet mounted over a larger metal ground plane. The flat metal sheet usually has a rectangular shape, and the metal layers are generally separated using a dielectric spacer. The flat metal sheet has a length and a width that can be optimized to provide a desired input impedance and frequency response. A dual polarization patch antenna can be configured to concurrently radiate horizontally and vertically polarized sinusoidal signals. Dual polarization patch antennas are popular because of their simple design, low profile, light weight, and low cost. An exemplary dual polarization patch antenna is shown in FIGS. 1A and 1B.
Additionally, multiple patch antennas on the same printed circuit board may be employed by high gain array antennas, phased array antennas, or holographic metasurface antennas (HMA), in which a beam of radiated waveforms for a radio frequency (RF) signal or microwave frequency signal may be electronically shaped and/or steered by large arrays of the patch antennas. An exemplary HMA antenna and a beam of radiated waveforms is shown in FIGS. 1C and 1D. Historically, the individual patch antennas are physically grouped closely together to shape and steer a beam of radiated waveforms for horizontally and/or vertically polarized sinusoidal signals. Unfortunately, cross polarization isolation of concurrently radiated horizontally and vertically polarized signals may be degraded by mutual coupling because of the close physical proximity of dual polarization patch antennas employed to radiate millimeter RF waveforms. New designs are constantly sought to improve performance, reduce mutual coupling, and further reduce cost. In view of at least these considerations, the novel inventions disclosed herein were created.